One of the stainless steel stiffening ribs used on windshield wiper blades may make an adequate tool for poking thru the insulation, depending on how far you need to go. I always keep a few ribs when I replace wiper blades on my Tiger (Chevy Silverado chassis), since they're nice and long. They're good for making a variety of improvised long, skinny tools.
You can bend the end of the rib double with pliers to form an eye, then put your wire into the eye, and squeeze the eye shut to hold the wire.
Jim, "Struggling hair farmer."